#include <stdio.h>

int main( )
{
    double d, vul;
    int t1, t2, t;
    while ( scanf("%lf%lf", &vul, &d) != EOF )
    {
        t1 = 1;
        t = t2 = 0;
        while ( vul > 0 )
        {
            t2++;
            if ( t2 > t1 )
            {
                t++;
                t1++;
                t2 = 0;
            }
            else
            {
                t++;
                vul -= d;
            }
        }
        printf("%d\n", t);
    }
    return 0;
}
